Geosporobacter subterraneus gen. nov., sp. nov., a spore-forming bacterium isolated from a deep subsurface aquifer

A novel, strictly anaerobic, chemo-organotrophic bacterium, designated strain VNs68(T), was isolated from a well that collected water from a deep aquifer at a depth of 800 m in the Paris Basin, France. Cells were thin, non-motile, Gram-positive rods forming terminal endospores (3.0-5.0 x 0.5 microm). Strain VNs68(T) grew at temperatures between 30 and 55 degrees C (optimum 42 degrees C) and at pH 5.6-8.4 (optimum pH 7.3). It did not require salt for growth but tolerated up to 40 g NaCl l(-1). Strain VNs68(T) was an obligate heterotroph fermenting carbohydrates such as glucose, xylose, fructose, ribose and cellobiose. Casamino acids and amino acids (arginine, serine, lysine, alanine, aspartate, asparagine, isoleucine, histidine) were also fermented. The main fermentation products from glucose were acetate with H(2) and CO(2). Sulfate, sulfite, thiosulfate, elemental sulfur, nitrate and nitrite were not used as electron acceptors. The G+C content of the genomic DNA was 42.2 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain VNs68(T) was affiliated to cluster XI, order Clostridiales, domain Bacteria. On the basis of 16S rRNA gene sequence comparisons and physiological characteristics, strain VNs68(T) is considered to represent a novel species of a new genus, for which the name Geosporobacter subterraneus gen. nov., sp. nov. is proposed. The type strain of Geosporobacter subterraneus is VNs68(T) (=DSM 17957(T) =JCM 14037(T)).